Means for presenting pictures in apparent three dimensions



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MEANS. EN WAREN THREE DIMENSIONs 2 Shee'tSmSnee't 2 .yf 7 77T, -Q/f Aja da@ 70, 2g

I Ef 45' ATTORNEY.

APPARTENT TH Nawoiiiclb Tanaka, Brooklyn, N.

Application August 2 o Claims.

The present invention relates to means for presenting pictures in apparent three dimensions, and more particularly to a refractive screen through which photographic or other perspective pictures may be made to appear with depth.

The invention resides on my discoveries.' l found that the eyes may perceive illusory third dimension in a picture, when viewed through a refractive screen which is adapted to refract rays of light coming from each small part of the picture plurally in different directions, preferably in such manner that one eye would perceive an image of each part of the picture in one direction, while the other eye would images of the same part in several slightly different directions This gives rise to plural intersections of visual lines from both eyes all on a single visual line, variously on the plane of the picture and in iront or at the back of the picture, depending upon the position of the eyes with respect to the screen. I found that one way to accomplish this universally for all intended viewing positions is by means of a screen of transparent sheets or plates having two superposed striped surfaces, one stliped with multitudinously recurring grooves and ridges of suitable contour and the other with a multitude of light admissive and interceptive stripes in suitable relative pitches. The spacing between the two surfaces is so adjusted that moire patterns manifesting to the eyes or a spectator at a suitable distance from the screen, as a result of the moire eiect due to the interaction of the striped surfaces, would appear with a pitch which enables the eyes to perceive images of each part of the picture by differently retracted rays through dissimilar parts of the moire patterns.

The above mentioned light admissive and interceptive stripes may be either opaque and transparent stripes or stripes functionally equivalent thereto such es stripes formed by deep cut grooves as will be later apparent.

As novel and distinguishing features or this invention, stressed is the functional relation between the two optical surfaces and the distance therebetween for creating a moire eiect of suitable pitches and utilizing it for the present purpose. While the construction of scroe of the in dividual grooved plates herein shown and Idescribed as suitable constituents of the screen may be known, the combination of two superposed surfaces of distinctly different designs having such characteristics capable to manifest moire eect as herein described is claimed to be basically new and so is the principle on which this invention operates.

5, 193g, Serial No., 223,212?

(Cl. 38m-24) t'mguishing a suitable In stereoscopes and all other stereoscopic devices which operate on the well known principle depending upon the coordination of left and right eye images, eyes are made to stereoscopically locus on each and all points in the view ior the same adjustment of the eyes. This would be an impossible feat for any pair oi eyes to perform in nature, wherein the objects in a view are at different distances from the eyes, and hence the image perceived by the occular sensory organs can not be exactly like what we perceive in the three dimensional space.

In contrast thereto, neither separate nor distinct left and right eye views are required in the present invention to attain, the purpose, since it does not rely on such pair or images which are vital requisites for every stereoscopic device, but ordinary photographs, photographic prints both in full and half tone and even certain other pern spective pictures may 'be effectively used and the result obtainable therewith is more natural in manifestation oi the third dimension than in the stereoscopic devices, rihis is another disieature of the invention.

l aware that an attempt has been made to obtain a three dimensional illusion by projecting a picture on a superposed series of finely embossed transparent sheets added in front of a projection screen, the idea being to obtain rays reected from a number of planes in addition to those reiiecting from the opaque screen. However, the images reflecting from several planes would be mutually displaced from one another, ditterently for each different angular position of viewing eyes, resulting to the limitation of effective viewing scope, even when inevitable blurring o images due to such arrangement is not considered. I am also aware that a similar attempt is recorded in which a projected picture is purposely blurred through a refractive screen to obtain a sort oi pseudo stereoscopic effect in the picture. As will be readily understood, in these schemes there is employed no denite means for coordinating mutually displaced images perceived -by the two eyes of a spectator in order to create the illusion.

The primary object o this invention is to provide means whereby photographs, photographic prints and certain other perspective pictures on either opaque, translucent or transparent carriers and projected pictures as in a motion picture or lantern slide projection may be presented in apparent three dimensions for a large viewing scope, without resorting to eye pieces.

Another object is to provide a displaying means wherein ordinary photographs and other pictures are made to appear with the third dimension, with or Without the benefit or a speciaily provided illuminating means.

A further object is to provide a projection screen unit for motion pictures by which pictures projected thereon may be perceived in apparent three dimensions, employing customary films and projectors.

A further object is to provide a picture frame in which a picture placed therein shows the depth illusionally.

A still further object is to provide an interu nally illuminated display apparatus wherein pictures may be presented in illusory three dimensions.

A feature of the invention is the employment of a screen adapted to derive a plurality of mutually displaced images or a dened image and trail-like images of a picture when the picture is viewed through it and to render the images differently perceptive to the two eyes of a spectator positioned within a certain viewing scope.

Another feature is the employment of a screen which comprises a mutitudinously grooved surface and light admissive and interceptive striped surface superposed a distance apart to obtain suitable moire effect so as to discriininately intercept mutually displaced images derived by the grooved surface of a picture placed at the back of the screen.

Another feature is the provision or" a screen as above in which the pitches of the recurring ridges and grooves and of the stripes of light admissive and interceptive strips and the distance therebetween are dirnensionally related to each other so as to manifest moire patterns of such pitches to the eyes of a spectator positioned within a predetermined effective viewing scope as to disoriniinately intercept the mutually displaced images derived by the grooved surface by exposm ing diierently displaced images to the eyes through dissimilar parts of the moire patterns.

A further feature of the invention is the einployment of a grooved plate in which the ridges and grooves are smoothly joined by curved groove walls into a wave or near wave formation for the purpose oi minimizing or virtually eliminating the distortion of images due to the moire effect that is otherwise conspicuous to viewing eyes.

A further feature is the employment oi two multitudinously parallel grooved surfaces, one adapted to derive a plurality oi images of a picture and the other to discriminately intercept said images, exposing differently retracted images to the eyes of a spectator positioned within an effective viewing scope through dissimilar parts of moire patterns produced by the interaction or" the grooved surfaces, for the purpose of obtain ing a three dimensional eiect and allowing more illuminating light to be transmitted therethrough to the picture.

A still further feature of this invention is the employment of two striped surfaces, either two grooved surfaces or surfaces one grooved and one opaque-transparent striped, in which the pitches of the stripes on the two surfaces are equal or somewhat or slightly dierent for securing a small moire variation for desired scope of viewing distance.

A still further feature is the employment of a grid intercepter to avoid surface refiection from a refractive screen.

With the above and other objects in view, the

invention comprises certain detail of construcaccessi tion and arrangement of parts as will be hereinafter more fully described, illustrated and claimed, the reference being had in the accompanying drawings which form a part of this speciiication.

In the drawings,

Fig. i is a iront view of a picture frame, partly broken away, embodying the invention;

Fig. 2 is a horizontal section of the above, taken along line 2--2 thereof;

Fig. 3 represents an enlarged perspective view of a fragment taken from one of the corners (3-3) oi the screen appearing in the preceding views;

Fig. e illustrates in perspective a partly open view of a projection screen unit, also an embodiment of the invention, for a motion picture or lantern slide projection;

Figs. 5 to i0 show various modifications of the refractor, a part of a refractive screen, in magnied iragmental section cut across the grooves thereon. Any one of these may be used as a component part of a refractive screen embodying my invention;

Figs. il to l5 illustrate enlarged fragmental views of various Inodications of the intercepter, another component oi the refractive screen;

Figs. 16 to 18 depict several combinations in perspective, as examples, of the parts illustrated in Figs. 5 to l5;

Fig. 19 represents a vertical sectional view of a display apparatus, an embodiment of the invention;

Fig. 20 graphically depicts the optical function of the reiractor with respect to rays coming from a given point of a picture.

Fig. 2i illustrates the optical function of the refractive screen;

Fig. 22 theoretically explains the function of the refractive screen with respect to the teamed eyes of a spectator, leading to the perception of depth in a picture; and

Figs. 23 and 24 are respectively a horizontal sectional view and a iront view of a magnified fragment of a grid screen or plate which is a modication oi the intercepter, Fig. 23 showing the relative position of this plate with respect to a reiractor.

Similar numerals designate throughout several views.

Referring to Figs. i and 2, numeral 2G designates e. trarne for pictures, having a somewhat deeper recess than a conventional picture frame. Clamped at the front part of the frame between the molding iii and a rectangular spacer 22, a reractive screen comprises a refractor 2t and an intercepter 23 in form of plates or sheets spaced a suitable distance apart by a second spacer 25 and secured together by a suitable means such as a paper hemming 26 to constitute a unit. Although it is preferable to have an air space between the reiractor and intercepter, the spacer may be a transparent plate of desired thickness to make a compact unit. The thickness of the spacer is determined from the desired distance between the functioning surfaces of the two plates in accordance to the mathematical formulae which will be given in the later part of this specification.

The plates of the screen are made of transparent material, such as transparent thermoplastics, for instances, cellulose of acetate or polymerized methyl methacrylate derivative, by molding or forming or by machining the grooves, or glass or like material may be used in cases similar parts when the grooving is not required to be too ilne for proper molding.

As illustrated in Fig. 3, the baci; plate or re tractor 2li has its grooved contour in form ci ridge and groove stripes which in this instance consist of parallel series of fiat ridges and curved groove walls, while the iront plate or intercepter t3 has one of its surfaces grooved to a parallel row of semi-cylindrical strips which are flattened at the middle parts and functionally equivalent to opaque and transparent stripes as will be later explained. rEhe grooved surfaces oi' the two plates are located confronting each other with the grooves on both surfaces set vertically in parallel or approximately in parallel to each other. The pitches of the ridge-groove stripes on both surfaces are equal or slightly different.

Behind the spacer 22, a picture or picture carrier 21 is held between plates 23 and 2E which are in turn pressed against the spacer i2 by a suitable locking means it goes without sa* ing that when a sti picture carrier is to be used. these plates become superrluous and therefore may be dispensed with.

The picture 2l may be illuminated through the screen or from the sides (see i9) via the transparent plate 2S or from the rear of the frame providing the baclr plate in translucent construction. Needless to add, the picture is to be viewed through the screen and the same goes in all cases herein referred to.

in Fig. il, within a frame 3l housing projection screen for a stili or motion picture a refractive screen is disposed. At the rear of the refractive screen and separated therefrom by a spacer there is located a light pervious and dispersive screen or heavily frosted glass or plastic material or the like. To gether with the trarne, these screens constitute a. projection screen. unit.

Although have illustrated in the drawings relative position of parts as they appear, it is to be understood that the dunensional proportion is by no means actual. For an example, 'the thick ness of the spacer or 25 is much exaggerated in comparison with that the spacer 2: or and so is the thickness of the screen plates. lThe dimensions oi the parts should be determined in accordance with the size or' pictures to be presented and the purpose for which the apparatus is intended, and it can be easily done guided by the formulae herein given.

The intercepter (front plate) may be any one of the deep cut grooved plates herein shown or an opaque-transparent striped plate f see 13) or may be a grid screen as shown in Figs. 23 and 2li. The grid screen may be constructed by cutting slits through any suitable sheeting or by joining strips or Wire strands with narrow horizontal bars as indicated by numerals and 3 in Figs. 23 and 2e. The grid is painted dead black to eliminate the surface reflection o light. I may employ such a grid screen instead of an intercepter oi transparent material, when the surface reflection is found to be annoying to spectators, or the provision of adequate sound channels therethrough is desired ior articulate cinematograph projection.

The reractor 2t' may be any one oi the .refractnr plates herein shown and described. These plates are suitably separated by a spacer 25 as in the previous views.

The projection screen unit above described may be adapted for an articulate cineznatograph projection either' by providing sound channels or' size required lfor Kit around the circumferential or slits which are represented by vertical lines ih Fig. 4 or multitude oi" perioratlons through the screen plates as indicated by numeral in Figs. 7 and i2.

Pictures ar the projection projected in operation directly on screen from a position some distance baci; oi the screen and presented through the r. active s reen '2d-JM' to spectators seated in ront (the left side) thereof within a predetermined eiective viewing scope.

in Figs. 5 to l), a double headed arrow 36 denotes the pitch of ridge-groove stripes on each plate. The other arrowed broken lines show the paths oi rays in traversing respective plates irl the direction of arrows, illustrating the refraction of rays by curved surfaces of each plate in contrast to substantially undeiiected rays through level or near level parts thereof.

in Fig. 5, the plate has a surface grooved in form of the stripes oi fiat ridges 3l and curved walls or urrotvs 38 like the refractor in Fig. 3.

In Fig. 6 the grooved surface has a contour of the stripes of at groove bottoms 39 and curved walls fill.

In Fig. 7, the refractive surface talles a contour oi flat ridges il?, flat bottoms and curved walls the latter smoothly joining the rst tivo. The wall surfaces should be considerably narrower than the .ridge or bottom Surfaces for better performance. -Note a perforation 35' for sound transmission.

Fig. 8 is a direct modication of Fig. 5, the hat ridges in the latter view being slightly curved to form a parallel rovv of elliptic convex cylindrical lenses.

Fig. 9 shows a modification oi the plate of Fig. 6, the bottoms oi the grooves being slightly curved to form a series of parallel concave or hollow cylindrical lenses with an elliptical curvature.

in Fig. i0, the proile oi the refractive surface of the plate appears in a recurring Wave formation, a modification of Fig. '7.

Any one of the above described plates may be used as the reractor o a refractive screen ernbodying the invention. However, discretion should be exercised in deciding the form or ren tractor according to the purpose and size oi apparatus in which it is to be incorporated.

When a reiractor such as shown in Figs. El and l0 is employed, it should bc remembered that every strip image perceived through a curved ridge will be laterally reversed, il a picture is placed beyond the local plane of the lenses.

ln Fig. il, one surface of the intercepter has a contour of parallel semi-cylindrical strips which may ce circularly or elliptically curved. Such plate, when viewed from the flat side, shows a distinct striped appearance see Fig. l'), the edge parts di of the strips functioning as opaque strips.

in Fig. i2, the top or middle part of each cylindrical strip of Fig. ll is flattened. The perforation is a sound channel.

In Fig. 13, an intercepter in form of an opaquetransparent striped plate is shown. The opaque strips fil may be obtained by printing black on a transparent sheet or plate or by lling parallel grooves cut or molded on a transparent plate with a suitable dead black material, such as crayon or ink. The opaque strips may be substituted by translucent or transparent color strips. when desired to tint the images perceived therethrough increase illumination. It is found that the opaque strips should be wider for better performance in comparison with the transparent strips, however the resultant loss of visual rays makes the Widening or" the opaque strips a matter of compromise.

In Fig. le, an intercepter has concave cylindrical strips which also show a striped appearance, when viewed from the flat side.

In Fig. 15, another modification of the intercepter is shown. This plate functions almost similarly as an opaque-transparent striped plate, the rather steep Walls fit being functionally equivalent to the opaque strips, Within a limited angular scope.

Any one of the intercepters shown in Figs. ll to may be employed as a component of a refractive screen embodying this invention, though some may be preferable to the others depending upon What purpose the nished apparatus will be used for.

In Fig. 16, the refractive screen comprises a reractor 2a as one in Fig. 7 and an intercepter 23" as one in Fig. 13. The opaque or interceptii'e strips are represented by shaded bands di.

In Fig. 17, the reiractor of Fig. 1G and intercepter of Fig. il are the components of a refractive screen, an embodiment of the invention. The interceptive strips 65" are shown through the transparent body by shaded bands.

In Fig. i8, a plate bears on one of its surfaces a series of parallel convex cylindrical strips as of Fig. 8 for the refractor and the other surface has the stripes of opaque and transparent strips for the intercepter, constituting a refractive screen, and embodying the invention.

The refractors and intercepters and the coinbinations thereof herein shown are by no means exhaustive as possible modications, but may be taken as fundamental examples.

ln Fig. 19, a side illuminated display apparatus is shown. When an opaque-transparent striped intercepter is used in the refractive screen, pictures on opaque carriers can be more eectively illuminated by this means.

The housing l2 has a iront window lli which is adapted 1o hold a re ractive screen comprising an opaquct"ansparent striped sheet 23" and grooved sheet 2&3" represented by heavy lineal as those shown in Fig. i6. These sheets are held separately between transparent plates which are shown in shaded sections. A back; Window @le is equipped with a picture frame fili. The screen and picture frame are suitably separated for the best performance.

A picture #l5 in the frame 155 is obliquely illuminated by lamps fil, Fil in the compartments at the top and bottom parts of the housing. In this means of illumination it is required to have an adequate space between the screen and picture for eiiective illumination. For small pictures and close viewing a iine grooving (say with 80 grooves or stripes per inch) is desirable and hence the requirement of comparatively wide spacing between the screen and picture calls for iiat ridged and/or lat bottomed refractor or a refractor having curved ridges and/or bottoms of small lens power in order to secure clear views.

In Fig. 20, the function oi a reiractor is illus-- trated. The mission of the refractor is to derive a plurality of mutually displaced images in viewing a picture therethrough, that is, to make a picture appear at a plurality of positions and if. attained by plurally refr-acting rays from each point of the picture to horizontally diiierent directions which vary in cycle multitudinously recurring as do the ridge-groove stripes. t is done in such manner that through the level (parallel to the plane of the plate) parts a fairly dened image of the picture is perceptible consisting of a multitude of parallel strip images and through the other parts groups of mutually displaced images or trail-like images, as of swiftly moving bodies, are perceptible on either sides of the rst image. In short the images of the picture are perceptible in a number of mutually displaced positions, most prominently in one position.

Referring to 20, numerals 2l and 2d designate horizontal sections of a picture and refractor respectively. The grooves are shown in much exaggerated form for the sake of illustration.

Ari eye fit viewing a small area 49 on the picture through the refractor 2t (temporarily forgetting the presence of a dash line 5U) perceives a plurality of images of said area, since a narrow beam represented by a ray 5i passing through a level surface of the refractor inpresses the eye with a little or no appreciable change oi direction, while beams presented by rays '252, etc. being retracted at respective groove walls 5t, 55 etc. reach the eye from diierent directions, resulting to the perception of the area i9 at several mutually displaced positions 39, 5S, il etc. The dot-dash lines indicate the visual lines to these positions.

As every small area of the picture would similarly impress the eye, the picture as a Whole will be perceived by the eye in a composite form of a fairly dened image overlappingly accompanied by traildike images on both sides thereof. As the number of beams contributing to the perception ci the trial-like images increases with the 'mcrease of the remoteness of the picture from the screen, the depth expression of the picture would be augmented by the increase of the spacing be tween the screen and picture.

Let the dash line 5d represent an opaquetrans parent striped intercepter as in Fig. 13, the horizontal section or" each opaque strip being represented by a dash. rhen it will be seen that some or the visual lines to the eye i3 are intercepted by opaque strips, resulting to discriminate obstruction of diilerently retracted rays and hence of dierently displaced images of the area. As will be readily understood, the discriminatory interception of the diierently displaced images varies with the horizontal position of the eye. The dotted lines indicate the obstructed visual lines. in this instance, the eye preceives only one oi the trail-like images consisting of a plurality of side images perceived by the ways of visual lines l8-52, i3- 5? etc. Assuming the eye remains stationary, the above aspect continues for an area around the area til. In another instance, the eye may perceive an area of the picture through level parts alone, receiving an impression of a dened image. In still other instances, the eye may perceive other areas of the picture in the other trail-like image or in the combination of a defined image and a trail-like image. When the eye is shifted horizontally with respect to the screen and picture, the aspect gradually varies with the movement of the eye. The above will be explained as a sequel of a moire eect.

Referring to Fig. 2l, the magnied horizontal sections of a picture 2l, refractor Eil and an inter epter 23 are designated by respective nu..

mei-als in accordance vith, Santing a small iragnleiu w.l lows Since a parallel rovi of convex cyl odrlcal function as opaquemtransparent s scriced in reference to ll. I interception ci the rays carla/Mln." area of a 'picture as explained i 20 would similarly te directioroA together with oteer likewise cost icute to the perception ol ari of the picture aggregated vertical strips which may appear as continuous Rays l, 6@ representant, other light proceeding irem the picture in direc e rl. rector l' but intercepted parte of e3 il drical sti'rzs on. the intacepter "fl and deecterl away from the cotirses L thereby en,

thus explaining the the edge 1s of @the strips.

other the cylindrical strips as intese.

Rays representing light proceef with tl the defined e perception rectloa` oi reir cti of the eye. at both groove Walls parts of cylindrical strips on f' be deleeted out ci: th eye with proloaoity formation oi trail-like As previously tioned, (or the intercepter soin f face of 1 ialici cylindrical leases as in and lo, every image strip perceived throug comes; cylindrical lens laterally revel.d but the reversal is not conspicuous, wh 1 the number of the strips ser unit ls sul large ier the eyes the intended viewing to make the image appear virtually con oneus, and therefore such lens strips are not datt-inien tal for the performance ci the invention.

It is irnos/'n that when two striped sos'iaces placed in superposing position and in close prorrimity with the strips in parallel or a so all angle, there will ce the manifestation of a plie nonenon called a moire effect. Similar .ect is manifested between two g'ooveol surfaces between a groovecl surface an opaque transparent striped surface, such as shown described herein, in similar position as alcove. When the recurring pitches of the grooves .and

ences) has1 sur lilorro and equal or nearly equal, a moire effect inevitably' reveals itself in patterns to a viewing eye, more or less iently depending upon a number of facclcding the relative pitches of the grooves stripes, the distance between the surfaces the surface contour of the back surface. 'moire pattern resembles the baci; surface :lah :to much maniifled scale. This pho hom-anon owes its manifestation to the conjunction o varied combinations of the strips on the two surfaces with the viewing eye in cyclically re- 'ing order. Hence, moire patterns appearing ori the seperposeo surfaces vary their lateral disioels v1 h the viewing distance and shift lng eye in the same or opposite dihe later referred to. pattern is an enlarged pseudo image oi grooves and ridges on the hack surface or a composite consisting of a number of mutually distacco images thereof in magnied scale, incidentally retaining,T diierently refractive property of dierent parts oi the grooveridge stripes, roughly at corresponding parts of the moire pattern. However, as the moire pattern, is a composite image of mutually displaced ima-ges oi the groove-ridge stripes, the refractive charact istics at various parts of the moire is likewise the composition of different refractive characteristics of adjacent parts of the aroove-l-idge stripes.

fr rough imitation of a moire pattern which he perceptible on a reractive screen is represented hy parallel broken lines in Fig. 4, slewing that when the stripes on both surfaces are parallel the resultant moire patterns run in e same direction, vertical direction as the the interpupillary distance and the pitch or" recurri g erently refractive parts of that teamed eyes would perceive the screen, so irrages a picture by dlssiinilarly refracted rays, the least con eicuoushess ci moire patterns is :der to present clear least cilspictures. For this reason sudo.. the surface contour of the reractive surace should be avoided.

.leaving rounded, all angular corners in and arcurld the grooves of the refractor, it will be found when a 'picture is placed behind the .reactive screesufficiently near thereto, moire on the screen become virtually, if not '3 imperceptible, unless the viewing eyes are `d horizontally :from one position to another. ac3-eased distance between the picture and screen, the 'moire patterns increase their prominence Wh h may result in certain distortion or ring of the view of picture. On the other the depth expression of the view becomes more prominent with the increased distance hetwcei" the picture and screen. Therefore, the delle ration of desirable distance between the picture and screen is a matter of compromise and can loe reached by trial and adjustment. However, the spacing" between these parts is partly dependent upon the scope of diierently refractive power of the refractive surface and hence einen the steepness of the groove Walls or the depth of the grooves. Smaller scope of refraction permits greater spacing without bringing out the undersirable elects.

the present screen is used for motion picture Torroja tions or for large picture displays.

toi/sed the distance between the screen pl l tor and an. intercepter thus for creating the condition by virtue ci a moire effect that the two eyes of a spectator would perceive images by rays coming from each small area a. picture through dissimilar parts oi moire patterns or for functionally enlarging the 'pitch o di'erently refractive cycles to the tune of the interpupillary distance, in order to have the intersections ci visual lines from the eyes on various planes; on the plane of the picture and on planes in front and at 'the bacs thereof certain combination, as will be subsequently described.

In Fig. 22, numerals 2l, 2d and 23 designate horizontal sections ci a plctiu'e, rei'actor and an intercepter, cut along a plane right angle to the grooves on the reiractor.

An interpupillary line, e, straight line connting the eye pupils of a spectator, is herein as surned to be in the horizontal direction. in accordance with normal viewing position. Hence, any references herein made to horizontal direction should be understood to mean the direc tion or interpupillary line.

Each of eyes and viewing a srnail area of the picture ill would perceive, in absence of the intercepter 23", one fairly defined image and trail-like images of the area as explained in reference to Fig. 29. The heavy broken line and heaiy dotted line denote the visual lines for the dened image and lighter broken and dotted lines those for the trail-like images. '.'ihree broiren or dotted lines on each side of the visual lines for the dened image represent a number of similar visual lines in respective neighborhoods for side images which contribute to the fornication o? the trail-like images.

These visual lines intersect at numerous post' tions: The visual lines for the defined image perceptible to the eyes meet substantially ai; the true position of the area. visual line for the defined image intersects with a numher oi visual lines for the 'traiblilre irnages, as tl, et and Se in iront and at the baci: or" the picture plane. Beside these intersections, there are intersections between the visual` lines for the trail-like images at other numerous positions, as at lll, ll, it and 33.

The function of the intercepter 23" is to intercept or obstruct some of the visual lines in order to reduce the number to a single group of siron ilar visual lines, as illustrated in reference to the heavy dash line E@ in 2G.

In Fig. 22, the heavy bent lines above and below the intercepter 23" represent parts two moire patterns in corresponding ridge groove contour ci the reractor, perceptible the left eye B3 represented by line G3' under the intercepter and perceptible to the right eye @Il by line tft above the intercepter, remembering that moire patterns perceptible to the eyes do not appear at the same position but are displaced from each other. The level and inclined parts of each bent line respectively represent such parts of the moire pattern, which are pseudo' images of the level and wall parts of a ridgegrcove stripe.

When the moire patterns appear to the eyes with suitable `horizontal pitches, all oi the visual rupted as indicated by dotted lines, trl-t3 being only imintercepted visual line to the eye ttl, and hence all perceptible intersections including eli, 65 and @l are on the same visual line Stute- 63. Some oi the visual lines to the other eye t3 l5 may also be in ercepted, for an instance, those indicated "cy dotted lines including the visual line defined image, or without including the latter.

Experiments with two differently colored eye 2li' pieces uninistalrably prove that when the eyes of a spectator are stereoscopically focused on an object, the image impressing his occular sensory organs is the image dominant over or more prominent than the other, whichever eye per- 2s ceives the dominant image. it is the image which perceived by one of the eyes more sensitive than the other and/or with more visibility on vthe object. If the images perceived by the two eyes equally prominent or nearly so, the

il? image impressing his sensory organs Will be aloi an object are more prominently perceived by one eye while the other parts by the other eye, the image that impresses the sensory organs will be a harmoniously joined `out unblenderl combination of the images of the parts dominantiy perceived by either eyes, but not a superimposed composite image of two perceived by the eyes. The dominated images manifest their presence oy functioning as coordinators with the dominant images in the perception of depth.

@-7 The image perceived along the visual line trl- Gli being more proin'aent than the others perceived alo g the other uninterrupted visual lines. it is the image which impresses the sensory organs, the images perceived by the eye G3 functioiiing as the coordinators in the perception ot' the tlurd dimension.

Thus each area of the picture is perceived by the eyes to ce on various intersections of visual lines on either one of the visual lines for the defined image, depending upon the position of the area with respect to the moire patterns perceptible to the eyes. When the screen is suffi cient y' cover a number oi. the moire cycles perceptible to the eyes at a given position,

0 the image .'fsnpressing the sensory organs as an image oi the picture would he the combination of vertical band images, every other band owing to the perception ci each eye.

5 Under such circumstance, the faculty of the occular sensory organs, it seems, is capable to rationalize the varied perception of apparent location oi each and every area o the picture and to place the area in appropriate order, giving 7g' rise to the perception of depth, as can be reasonably deduced from 'the faculty shown by the organs in the pseudo stereoscopic perception in a photograph when viewed by one eye alone and the perfectly matching connection of two diiferent images of an object perceived by two eyes, to say nothirw stereoscopic percen tion.

For determining appropriate relative sions of the pitches oi? the grooveridge sti and light admissive-interceptive stripes and the spacing therebetween to obtain desired moire effect, the subsequent description is as .13. f reference.

Assuming for the fluidas-lent the striped la parallel to each other, stripes on doth surfaces are uniform throughout the and all stripes on o th suraces are parallel to one other, the diiriensional relation between the Bitches of a moire pattern and the stripes on the intercepter and reractor, respectively denoted by P and P" with to the spacing S between the two surr ces and the vier J di tance D (measured from intercepter surface) may be expressed oy the formula l DPH "ect is a result oi cyclic ive position oi stripes on 'tv/'o surfaces with respect to a viewing efe, the nurnber of moire occurrences inust equal to d erence hetween the num sers or st. pes on the two surfaces within :tor l two given visual lines the eye. f dtlis of Since the nioir variation in the i ne the two striped surfaces Within said angle Will have ratio lil-i-S/D. l/P and l/F respecm tively express the exact numbers, meaning to inw clude fractions any, of stripes length on the intercepter and r ractor. Eer-nce, tale ing the width of the tercefer part nuthin the angle as unit lens' .c the oi the numbers of stripes vrlthir; the angle is D+S l i i *Sm "Il"" l5'f mi The above is equal to the nuinher of -moire cycles Der unit length, which may be a traction. reciprocal of the above Value is therefore equal to the moire pitch.

When the pitches oi stripes on the tivo surfaces are equal the formula is sirnplided to to. great. This distance may he expressed by the formula point. Then We have by a simple geometrical process The value or" D expresses the nodal distance and can loe easily derived from the above equation The viewing plane at the distance may be called the nodal plane of the screen.

iractice, 'he spacing S the stripes. surlaces srnall, an eye at the .nodal plane may perceive o sets of moire hands moving in opposite dil tions when the eye is horizontally shifted, unl both striped suriaces are perfect ly and i parallel.

`" i the pitch of the stripes the interfv'hen is greater than P',

pedal L lane appears irl front oi the screen at which the lateral moire pattern with the viewing eye reversc ts direction. When the viewing distance is gi atei' than SlD/(PP'), the pattern sh s with the eye in the opposite direchave one's eyes perceive images of ft of a picture through dissimilar .cire patterns, the pitch or the moire ercel ed by each eye should have a a certain limit.

formulae herein given, suitable s ridge-groove stripes on a refractor and light intero s appropriate spacing therebetween oe determined to secure the maximum erective scope viewing distance for any given oi pictures and intended viewoen the pitches of stripes on the two surfaces are equal, the moire pitch increases proportionahy with the viewing distance, while the displacement ci moire patterns perceptible to tear eyes remains constant.

@n the other hand, with the pitch of the stripes on the intercepter slightly smaller or greater "1 an on the re: actor, rnoire pitch can be lient nearly constant `seyond a certain viewing` t be inept suino iractive deviv From the ently large with the aid of the retion for long distance viewing.

Jgoing description taken in conaccompanying drawings, the `rangement of parts and the will he readily understood d in the art to which this invention appertains, and While shown and descrioed ap "atus as now thought to be the liest ernhom :rents oi the invention, l Wish to understood that the apparatus herein d described are merely illustrative and such changes or modifications .may de, when desired, as to fall Within the scope s l. il. screei.i lor presenting pictures in apparent three dimensions, having a refractive surface and an interceptive surface superposed in close proximity to each other, said refractive surface provide-:l with grooves having curved walls interposed by piene strip parts and said interceptive surface provided with the stripes of light transparent and interceptive parts substantially in parallel to said grooves; the numbers of said grooves and interceptive parts laterally per unit length being at least approximately equal, and the structural and positional relation of the parts being such that bundles of dial lines drawn through said transparent parts from point directly in the front of and a distance from said interceptive surface embrace more plane parts than curved parts at some portions and vice versa e otier portions of said refractive surface.

2. A screen for presenting pictures in apparent three dimensions, having a refractive surface and an interceptive surface in close proximity to each other, said refractive surface provided with piane and curved parts in a stripe pattern in terceptive surface provided vvit'n light interceptive and transparent parts also in a stripe pattern, running substantially in the saine direction with the plane and curved parts; the numbers ci said curved parts and interceptive parts per nnit length being at least approximately equal, and the structural and positional relation between the parts being such that bundles of radial lines drawn through the transparent parts from a point directly in the front 0i and at distano from said interceptive surface embrace more plane parts than curved parts at some portions and Vice versa at the other portions of said refractive surface.

3. A screen for presenting pictures in apparent three dimensions, provided with a refractive element and an interceptive element o' transparent material contiguousiy superposed, refractive element having grooves with curved Walls interposed by plane strip parts and said interceptive element having light interceptive strips interposed by transparent strips substantiaily in alici to said grooves; the numbers of said plane strip parts and. transparent strips per unit length being approximately equal, and structural and positional relation between the parte being such that bundles of radial lines drawn through said transparent strips from a point directly in the front of and at a distance rorn interceptive element embrace more curved walls and less plane strip parts at some portions and vice versa at the other portions on refractive element.

fl. A screen 'or presenting pictures in apparent three dimensions, having a refractive surface and an interceptive surface superpcsed in close prox iraity to each other, said refractive surface provided with plane and curved strip parts smoothly continuing without angular kinks and said interceptive surface provided with the stripes of light transparent and interceptive parts, running substantially in the same direction with said plane and curved. strip parts; tile numbers of said plane strip and transparent parts unit length at least approximately equal, and the structural and positional relation between the parts being such that bundles or' radial lines drawn through the transparent parts irorn a point directly in the front or and at a distance from said interceptive surface embrace more plane and less curved parts at some portions and vice versa at the other portions of said refractive surface.

5. .a screenfor presenting pictures in apparent three dimensions, comprising a transparent plate of small thickness, provided with a refractive sur- :face 'which consists of a multitude of groove surfaces with curved Walls and plane strip parts in a stripe pattern and an interceptive surface which carries interceptive strip parts interposed by transparent strip parts running substantially in the carne direction with said groove surfaces; the numbers of the groove surfaces and interceptive strip parte per unit iengtli being at least approximately equal, and the structural and positional relation between the parte being such that bundles of radial lines drawn through said transparent strip parts from a point directly in the iront of and at a distance from said interceptive surface embrace more plane strip parts than curved groove Walls at some portions and vice versa at tire other portions of said refractive surface.

6. The combination with a picture receiving element; or" a screen described in cla-im l for presenting pictures in apparent three dimensions disposed in the iront of said picture receiving element a distance away.

NAWOKCl-l TANAKA. 

